Electrical apparatus



Oct. 6, 1931. L A. M. PHELAN 1,826,571

ELECTRICAL APPARATUS Filed NOV. 25, 192'?` annum-lun n. r11/,an f aangaan aunnunga/uurn Patented Oct. 6, 1931 y* UNITED STATE- s IAJIENTV loFF-lele:v

LOUIS A. M. PHELAN, F ELKEART, INDIANA, ASSIGNOR, BY MESNE ASSIGNMENTSJTO MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, OF MINNEAPOLIS, MINNESOTA A CORPORATION or DELAWARE ELECTRICAL APPARATUS Application led November 25, 1927. Serial No. 235,434.

The present invention relates to electrical apparatus and it has special referenceto electrical contact-making devices comprlsing spaced electrodes that are sealed into a closed container and are adapted to be brought into electrical conducting relation with one another through thev agency of a movable conducting body, 'preferably a fluidsuch as mercury, likewise disposed in said container and which, on being tilted, vis instrumental in performing the circuit-closing and c' `cuit-opening functions of the device.

More"particularly the invention refers to an electrical c ontactor device of the character indicated above, which will operate for long periods of time and serve to make and break comparatively large amounts of current without deterioration in any of its parts.

The present invention pertains to an electrical contactor device, as described above, which, if desired, may comprise a cylindrical -elongated tube, preferably in the form of a tubular container, that serves to house electrodes and a body of conducting fiuid such as mercury, the latter being adapted to bridge the electrodes within the tube. The tube 1s preferably disposed .when installed, to occupy normally a position neighboring on the horizontal and is suitably supported so that it may be tilted in either direction and thus alldw the conducting` Huid to iow into and' out of circuit-making position at the expense of very little energy. Y

The present invention also comprises such an arrangement -of the parts within the elec.- trical contactor device that the electrical current passing through the same will be interrupted by the breaking of the continuity of conducting fluid, instead of a break in contact between such Huid and a solid conductor.

Furthermore, the present invention also rovides an internal dam in the container that iiouses the electrodes and the conducting fluid, so that the conducting fluid will be broken up into two unequal parts, both of which remain in electrical contact with solid conductors. This dam is preferably inclined on onefside so that the conducting iuid when it breaks apart will do so rapidly, while the larger part of theluid will roll away from ing uid will be prevented from rupturing the container or the internal dam. This heatlnsulatlng dam is retained in position within the container by any convenient means such as by making it suiiciently resilient to enable 1t to expand slightly or spring into place within thel container; by providing grooves havlng expansible resilient material disposed therein; or by cementing the same to the internal walls of the container. A further object of this invention is to provide a contacter device of the type indicated above that will be simple and economical to construct and will possess a long life even when subjected to considerable quantities of electric current at substantial voltages.

Further vobjects will appear upon reference to the following description and accompany ing drawings, in which Figure 1 is a vertical sectional view of one.

modication of the device embodying the present invention;

Fig. 2 isa similar view showing a further modiication Fig. 3 is a side elevation of one of the i11- serts or dams, showing one means of securing shown inl Fig. 5

, Fig. 7 is a vertical sectional view of another modification of the device embodying the present invention, in which case the dam has a special shape;

Fig. v8 is a vertical sectional view of still a further modification of the device; and

Fig. 9 is a perspective view of a dam as shown` in Fig. 8.

90 f employed in the interior of the container Referring to Figs. 1, 2, 4, 5, 7, and 8, the device preferably comprises, in a general way, a cylindricalv and elongated `container 11 made preferably of an insulating material, such as glass, housing a pair of electrodes or contact members 12 and 13, which are disposed apart within thecontainer 11, and are adapted to make electrical contact with a conducting Huid, which may comprise mer- Acury,'14 and l4-a. In order to ensure the breaking up of the mercury into 'two portions when the current is to be interrupted, a dam. or obstruction 15 is' placed 'within the tube, being preferablyl so positioned that a large body of mercury 14 and a smaller body of mercury 14--a will be produced when the container is slightly tilted in one direction, which', in the drawings, would be to the right. On slightly tilting the container to the left;v the larger body of mercury 14 will rise over .the dam 15, and, uniting with the smaller e body of mercury lll- (1, will establishan electrical conducting path between the electrodes 12 and 13. Y

In order to make it easy'for the mercury to rise over the dam when the circuit 'is to be closed, the dam is preferably made inclined on the side toward the larger body of mercury. In order tol bring about a sudden break in the current, however, when the same is to` be interrupted, the dam is substantially rightangled at the side toward the smaller body of mercury 14`a. Thus. when the container is tilted tothe right, the mercury will pass through or over the dam 15, the body of mercury becoming attenuated as the greater part f of it flows to the right; Finally, and sudsection and made of an heat-resistant or redenly, the column of mercury still connectingl the two portions 14`av and 14 will break apart, and 'the portion 14 will thu'sbe isolated. By reason ofthe inclined sides of the dam 15, the mercury will rapidly roll away from the smaller portion 11i-a, SO that any electric arc produced during the break will be but of short duration. The end portion of the electrode 13 extends within the dam 15. The foregoing construction ensures that the electric arcs on the breaking of the circuit through the contacter will alwavs occur over the dam 15 and thus preclude the arcs from damaging the walls vof the container 11.

Thev dam 15 may have several di Herent shapes. For example in Fig. .1, the dam con-V sists of a tubular member having a dtriangular t fractory material such as ignited soap stone, sometimes termed lava or of a similar hard inert and heat-insulating materiaL'provided only that the same i's of a nature that will not react with the mercury, norcause the contamipation of thelatter or deterioration of the bontactor. Preferably, also, the material constituting the dam should be non-wettabl'e n 'by mercury, and should be slightly roughened nazcan so'thattheqmercury will pass rapidly over f the same without in any way adhering to it.

Asillustrated in Figs. 1 and 2, the tubuy lar dam is kept in place within the container 11 by being provided with one or more cylindrical springs 16or other suitable resilient material serving as a; packing, disposed in thegrooves \17 in' the dam 15; `as more clearly shown in the elevational view in Fig. 3. These 'springs are vsplit at their ends, somewhat after ,the fashion of a piston ring. In placing the dam 15 within the container 11, the springs 16 are placed into the grooves 17, are then compressed so that they lie totally within the groove, whereupon the entire assembly iswpushed into the glass container. The natural resilience of thesprings 16 will hold the dam 15 in whatever position `ithas been placed in.. If the springs are tmade osuita'ble material, such as being covered with-iron, platinum, or made of chromium steel or nickel or tungsten, this will be satisfactory, as ,these materials are not adverselyafected by the mercury.

` The electrodes 12 and 13 are preferably made of a metal or'other conducting substance that does not chemically react with the mercury. This may be pure.tungsten;

or iron; or iron alloyed with chromium, or any metal which exhibits substantially no tendency to amalgamate withthe mercury or contaminate the mercury. The lead-in wires should be of such composition that a tight seal with the glass walls of the container is secured. Dumet wire, vwhich is very suitable for the purpose, may be used for the lead in, but it should be understood that none of this Dumet,wire must be eX- posed on the inside of the glass container, as

.the copper coating upon the sameV would amalgamate'with and contaminate the mercury. Preferably,I pure iron is used forl the electrodes 12 and 13. The vmaterials enteringv in the construction of my present 'contactor and the method of connecting the electrodes to the leading-in conductors, sealed in the walls ofthe container, may be those described respectively in U. S.- Patents No; 1,598,874-and No. 1,598,875.

Referring -to Figs. 1 and 2, it will be seen that electrode 13 extends for al considerable distance into the tubular dam 15, so that 'irrespective of the position of the tube, within reasonable limits, the mercury will be in contact with the electrode 13. This ensures that the electric arc will always occur 'upon the dam 15. In Fig. 1 theelectrodes 12 and 13 are shown entering the tube from the top, but they may also enter from the bottom, as shown in Figs.'2 and 4.

"An alternative construction is shown in Fig. 4. In this casethe dam 15, which consists of a tubular member of heat-insulating material, is supported within the glass contame'r 11 by means of-a suitable cement. It l Asbestos powder, Mg3Si2O7,7H2O

is desirable that such cement have a coeiiiycient of expansion approximately the same as that of the material composing the container, as otherwise the alternate heating and cooling of the dam may cause the container `when the container 11 is made of glass and the dam 15 is made of a good grade of' porcelain may comprise a mixture of aluminum oxide, asbestos and sodium silicate, otherwise known as waterglass. A suitable formula is Parts Aluminum oxide, A1203 30 0 Sodium silicate, Na2Si4O9,

suiiicient to make a syrup-like paste.

The nearer the coefficient of expansion of the glass is to that of the porcelain dam, the less asbestos is to be used in the above formula. Magnesium silicate, MgSiOs, magnesium oxide, Mg, may replace the asbestos. The sodium silicate may alsoI be diluted with some waterl before use. that has proven satisfactory is one made up of a mixture of lead phosphate, Pb3(PO4)2 `and sodium silicate. This is especially desirable when the glass employed has a high coeiiicient of expansion.

A further modification of my present contactor is that shown in Figs. 5 and 6. In this case the dam consists of a split tube" of insulating material that will Aexhibit suiiieient resiliency so that when vlongitudinally cut open, as shown in cross-section in Fig. 5, it will tend to expand slightly, so that it will hold itself in place when compressed, inv serted into the tubular container, and then `allowed to expand itself against the inside will allow of cementing to the bottom ofthel container 1`1 by meansof a cement such as already described herein.

substantially at the same point at each make and break, a protrusion 15'a on the insulating material 15 is provided.I

uIn'order to cause a larger amount of mercury. to be-retained in contact with the electrodef12, the container 11l may be expandedA Another cement To ensure that the body of mercury will break rapidly and' ing an annular projection' 15-a; although the construction of the dam may be similar to that shown in Fig. 7. The electrode 13 is so shaped and disposed that the end of the same extends for a distance into or upon the dam 15, this feature being characteristic of alll of the specific constructions shown herein. i

l/Vherever the springs 16 are`not shown, the dam 15 is either held in place by its own resilience and by being split, or is held to the container by means of one of the cements, or their equivalent, as herein disclosed.

After the dam, electrodes and mercury have been placed in the container 11, the same is evacuated of all gases therein contained, and then the container is filled with hydrogen, or similar inert gas, so that the container will house no gas capable of oxidizing or of otherwise deleteriously reacting with the mercury or any of the materials within the container. The pressure of this gas may be equal to that of the atmosphere, or be subatmospheric or even at more than atmospheric pressure.

Some of the advantages accruing from the improved construction of my present invention are as follows:

-In the first place the make and break in the electrical circuit occurs between .mobilel masses of mercury, and not between solid electrodes and mercury; second, any heat produced by the electric arcs obtaining at the point of break is kept away from the lwalls of the container, so that the latter will not be liable to fracture by sudden expansion; third, only a slight tilting of the container is necessary to effect the make or break; fourth, both bodies of mercury are alwaysin direct metallic contact with the electrodes so that at no time is there any possibility of any arc'forming between anything but mercury and mercury; fifth, by reason of the inclined sides of the dam, as shown in Figs. 1, 2, 4, 5, and 7,.the break will be sudden and themercury will roll away after such Vbreak,.or,as shown in Figs. -7 and 8, the

tions, over the highly refractory and heat resistant material composing the darn-15.J

By virtue 'of the construction of the elec-l trical contactors described in the present application, it is possible toA employ them for regulating electrical ,apparatus that requires, comparatively heavy current where strong arcing occurs..v

The types of contactors as above described. j i

electrical circuits carrying substantial curthe contactor is tipped into conducting posirents at comparatively high voltages, without deterioration.- Such a deviceobviously has a great many advantages over any former type of liquid contacter, since very little energy is required to tilt the contactor into and out of circuit-makingI and circuitbreaking positions, and, at the same time, the device is designed to be placed directly in series with -the electrical apparatuscon'- trolled thereby. l

Whilethere have been shownv and described several embodiments of the present invention, it is to be understood that many,

modiiications maybe made therein without departing from the spirit and scope of the appended claims, and-I desire that only such limitations shall be imposed uponthis invention as are, specifically pointed out in the lclaims and such as are required by the prior art.

Having thus described the invention, what is claimed, as new and desired to be secured by Letters Patent in the United States, is

l. In an electrical contacter of the type de` scribed, a refractory dam consisting of a split tapering walled tube of refractory material.

In an' electrical contacton of the type described, a dam consisting of a split tu e of refractory material.

3. In an electrical contactor'of the type described, a damfconsisting of a split tube of refractory material not adversely affected by mercury, said dam being cemented to the walls of the container.

4; A tiltable electrical contactor comprising anhermetically sealed container, elec-- trodes spaced vapart within said container,

l material not adversely affected by mercury a dam consisting of'a split tube of refractory material'between said electrodes, a body of metallic conducting fluid, andan atmosphere of gas housed withln said container. f

5. A tiltable electrical contactor comprising an hermetically sealed container, electrodes spaced apart within said container, a dam consisting of a split tube of refractory in said container and disposed between said electrodes, a body of mercury adapted to establish a path for electric current between said electrodes and of sufficient quantity to cover said dam when the contactor is tipped into conducting position, and an atmosphere of hydrogen withirr` said container.

6. A tiltableI electrical contacter comprising an hernetically sealed'rglass contamer, metallic electrodes of a materlal not adversely affected by mercury spaced apart within said container, a dam consisting of a split tube of, refractory material nonwettable by mercury dis osed in said container between sald electro es, a bodyfof mercu 'I to connect electrically said electro es and of suiiicient quantity to cover said dam vwhen adapted LOUIS A. M. PHELAN. 

